/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Copyright 2011, Blender Foundation.
 */

#include "COM_ScreenLensDistortionOperation.h"

extern "C" {
#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_rand.h"
#include "PIL_time.h"
}

ScreenLensDistortionOperation::ScreenLensDistortionOperation() : NodeOperation()
{
  this->addInputSocket(COM_DT_COLOR);
  this->addInputSocket(COM_DT_VALUE);
  this->addInputSocket(COM_DT_VALUE);
  this->addOutputSocket(COM_DT_COLOR);
  this->setComplex(true);
  this->m_inputProgram = NULL;
  this->m_distortion = 0.0f;
  this->m_dispersion = 0.0f;
  this->m_distortion_const = false;
  this->m_dispersion_const = false;
  this->m_variables_ready = false;
}

void ScreenLensDistortionOperation::setDistortion(float distortion)
{
  m_distortion = distortion;
  m_distortion_const = true;
}

void ScreenLensDistortionOperation::setDispersion(float dispersion)
{
  m_dispersion = dispersion;
  m_dispersion_const = true;
}

void ScreenLensDistortionOperation::initExecution()
{
  this->m_inputProgram = this->getInputSocketReader(0);
  this->initMutex();

  uint rng_seed = (uint)(PIL_check_seconds_timer_i() & UINT_MAX);
  rng_seed ^= (uint)POINTER_AS_INT(m_inputProgram);
  this->m_rng = BLI_rng_new(rng_seed);

  this->m_cx = 0.5f * (float)getWidth();
  this->m_cy = 0.5f * (float)getHeight();

  /* if both are constant, init variables once */
  if (m_distortion_const && m_dispersion_const) {
    updateVariables(m_distortion, m_dispersion);
    m_variables_ready = true;
  }
}

void *ScreenLensDistortionOperation::initializeTileData(rcti * /*rect*/)
{
  void *buffer = this->m_inputProgram->initializeTileData(NULL);

  /* get distortion/dispersion values once, by reading inputs at (0,0)
   * XXX this assumes invariable values (no image inputs),
   * we don't have a nice generic system for that yet
   */
  if (!m_variables_ready) {
    this->lockMutex();

    if (!m_distortion_const) {
      float result[4];
      getInputSocketReader(1)->readSampled(result, 0, 0, COM_PS_NEAREST);
      m_distortion = result[0];
    }
    if (!m_dispersion_const) {
      float result[4];
      getInputSocketReader(2)->readSampled(result, 0, 0, COM_PS_NEAREST);
      m_dispersion = result[0];
    }

    updateVariables(m_distortion, m_dispersion);
    m_variables_ready = true;

    this->unlockMutex();
  }

  return buffer;
}

void ScreenLensDistortionOperation::get_uv(const float xy[2], float uv[2]) const
{
  uv[0] = m_sc * ((xy[0] + 0.5f) - m_cx) / m_cx;
  uv[1] = m_sc * ((xy[1] + 0.5f) - m_cy) / m_cy;
}

void ScreenLensDistortionOperation::distort_uv(const float uv[2], float t, float xy[2]) const
{
  float d = 1.0f / (1.0f + sqrtf(t));
  xy[0] = (uv[0] * d + 0.5f) * getWidth() - 0.5f;
  xy[1] = (uv[1] * d + 0.5f) * getHeight() - 0.5f;
}

bool ScreenLensDistortionOperation::get_delta(float r_sq,
                                              float k4,
                                              const float uv[2],
                                              float delta[2]) const
{
  float t = 1.0f - k4 * r_sq;
  if (t >= 0.0f) {
    distort_uv(uv, t, delta);
    return true;
  }
  else {
    return false;
  }
}

void ScreenLensDistortionOperation::accumulate(MemoryBuffer *buffer,
                                               int a,
                                               int b,
                                               float r_sq,
                                               const float uv[2],
                                               const float delta[3][2],
                                               float sum[4],
                                               int count[3]) const
{
  float color[4];

  float dsf = len_v2v2(delta[a], delta[b]) + 1.0f;
  int ds = m_jitter ? (dsf < 4.0f ? 2 : (int)sqrtf(dsf)) : (int)dsf;
  float sd = 1.0f / (float)ds;

  float k4 = m_k4[a];
  float dk4 = m_dk4[a];

  for (float z = 0; z < ds; ++z) {
    float tz = (z + (m_jitter ? BLI_rng_get_float(m_rng) : 0.5f)) * sd;
    float t = 1.0f - (k4 + tz * dk4) * r_sq;

    float xy[2];
    distort_uv(uv, t, xy);
    buffer->readBilinear(color, xy[0], xy[1]);

    sum[a] += (1.0f - tz) * color[a];
    sum[b] += (tz)*color[b];
    count[a]++;
    count[b]++;
  }
}

void ScreenLensDistortionOperation::executePixel(float output[4], int x, int y, void *data)
{
  MemoryBuffer *buffer = (MemoryBuffer *)data;
  float xy[2] = {(float)x, (float)y};
  float uv[2];
  get_uv(xy, uv);
  float uv_dot = len_squared_v2(uv);

  int count[3] = {0, 0, 0};
  float delta[3][2];
  float sum[4] = {0, 0, 0, 0};

  bool valid_r = get_delta(uv_dot, m_k4[0], uv, delta[0]);
  bool valid_g = get_delta(uv_dot, m_k4[1], uv, delta[1]);
  bool valid_b = get_delta(uv_dot, m_k4[2], uv, delta[2]);

  if (valid_r && valid_g && valid_b) {
    accumulate(buffer, 0, 1, uv_dot, uv, delta, sum, count);
    accumulate(buffer, 1, 2, uv_dot, uv, delta, sum, count);

    if (count[0]) {
      output[0] = 2.0f * sum[0] / (float)count[0];
    }
    if (count[1]) {
      output[1] = 2.0f * sum[1] / (float)count[1];
    }
    if (count[2]) {
      output[2] = 2.0f * sum[2] / (float)count[2];
    }

    /* set alpha */
    output[3] = 1.0f;
  }
  else {
    zero_v4(output);
  }
}

void ScreenLensDistortionOperation::deinitExecution()
{
  this->deinitMutex();
  this->m_inputProgram = NULL;
  BLI_rng_free(this->m_rng);
}

void ScreenLensDistortionOperation::determineUV(float result[6], float x, float y) const
{
  const float xy[2] = {x, y};
  float uv[2];
  get_uv(xy, uv);
  float uv_dot = len_squared_v2(uv);

  copy_v2_v2(result + 0, xy);
  copy_v2_v2(result + 2, xy);
  copy_v2_v2(result + 4, xy);
  get_delta(uv_dot, m_k4[0], uv, result + 0);
  get_delta(uv_dot, m_k4[1], uv, result + 2);
  get_delta(uv_dot, m_k4[2], uv, result + 4);
}

bool ScreenLensDistortionOperation::determineDependingAreaOfInterest(
    rcti * /*input*/, ReadBufferOperation *readOperation, rcti *output)
{
  rcti newInputValue;
  newInputValue.xmin = 0;
  newInputValue.ymin = 0;
  newInputValue.xmax = 2;
  newInputValue.ymax = 2;

  NodeOperation *operation = getInputOperation(1);
  if (operation->determineDependingAreaOfInterest(&newInputValue, readOperation, output)) {
    return true;
  }

  operation = getInputOperation(2);
  if (operation->determineDependingAreaOfInterest(&newInputValue, readOperation, output)) {
    return true;
  }

  /* XXX the original method of estimating the area-of-interest does not work
   * it assumes a linear increase/decrease of mapped coordinates, which does not
   * yield correct results for the area and leaves uninitialized buffer areas.
   * So now just use the full image area, which may not be as efficient but works at least ...
   */
#if 1
  rcti imageInput;

  operation = getInputOperation(0);
  imageInput.xmax = operation->getWidth();
  imageInput.xmin = 0;
  imageInput.ymax = operation->getHeight();
  imageInput.ymin = 0;

  if (operation->determineDependingAreaOfInterest(&imageInput, readOperation, output)) {
    return true;
  }
  return false;
#else
  rcti newInput;
  const float margin = 2;

  BLI_rcti_init_minmax(&newInput);

  if (m_dispersion_const && m_distortion_const) {
    /* update from fixed distortion/dispersion */
#  define UPDATE_INPUT(x, y) \
    { \
      float coords[6]; \
      determineUV(coords, x, y); \
      newInput.xmin = min_ffff(newInput.xmin, coords[0], coords[2], coords[4]); \
      newInput.ymin = min_ffff(newInput.ymin, coords[1], coords[3], coords[5]); \
      newInput.xmax = max_ffff(newInput.xmax, coords[0], coords[2], coords[4]); \
      newInput.ymax = max_ffff(newInput.ymax, coords[1], coords[3], coords[5]); \
    } \
    (void)0

    UPDATE_INPUT(input->xmin, input->xmax);
    UPDATE_INPUT(input->xmin, input->ymax);
    UPDATE_INPUT(input->xmax, input->ymax);
    UPDATE_INPUT(input->xmax, input->ymin);

#  undef UPDATE_INPUT
  }
  else {
    /* use maximum dispersion 1.0 if not const */
    float dispersion = m_dispersion_const ? m_dispersion : 1.0f;

#  define UPDATE_INPUT(x, y, distortion) \
    { \
      float coords[6]; \
      updateVariables(distortion, dispersion); \
      determineUV(coords, x, y); \
      newInput.xmin = min_ffff(newInput.xmin, coords[0], coords[2], coords[4]); \
      newInput.ymin = min_ffff(newInput.ymin, coords[1], coords[3], coords[5]); \
      newInput.xmax = max_ffff(newInput.xmax, coords[0], coords[2], coords[4]); \
      newInput.ymax = max_ffff(newInput.ymax, coords[1], coords[3], coords[5]); \
    } \
    (void)0

    if (m_distortion_const) {
      /* update from fixed distortion */
      UPDATE_INPUT(input->xmin, input->xmax, m_distortion);
      UPDATE_INPUT(input->xmin, input->ymax, m_distortion);
      UPDATE_INPUT(input->xmax, input->ymax, m_distortion);
      UPDATE_INPUT(input->xmax, input->ymin, m_distortion);
    }
    else {
      /* update from min/max distortion (-1..1) */
      UPDATE_INPUT(input->xmin, input->xmax, -1.0f);
      UPDATE_INPUT(input->xmin, input->ymax, -1.0f);
      UPDATE_INPUT(input->xmax, input->ymax, -1.0f);
      UPDATE_INPUT(input->xmax, input->ymin, -1.0f);

      UPDATE_INPUT(input->xmin, input->xmax, 1.0f);
      UPDATE_INPUT(input->xmin, input->ymax, 1.0f);
      UPDATE_INPUT(input->xmax, input->ymax, 1.0f);
      UPDATE_INPUT(input->xmax, input->ymin, 1.0f);

#  undef UPDATE_INPUT
    }
  }

  newInput.xmin -= margin;
  newInput.ymin -= margin;
  newInput.xmax += margin;
  newInput.ymax += margin;

  operation = getInputOperation(0);
  if (operation->determineDependingAreaOfInterest(&newInput, readOperation, output)) {
    return true;
  }
  return false;
#endif
}

void ScreenLensDistortionOperation::updateVariables(float distortion, float dispersion)
{
  m_k[1] = max_ff(min_ff(distortion, 1.0f), -0.999f);
  // smaller dispersion range for somewhat more control
  float d = 0.25f * max_ff(min_ff(dispersion, 1.0f), 0.0f);
  m_k[0] = max_ff(min_ff((m_k[1] + d), 1.0f), -0.999f);
  m_k[2] = max_ff(min_ff((m_k[1] - d), 1.0f), -0.999f);
  m_maxk = max_fff(m_k[0], m_k[1], m_k[2]);
  m_sc = (m_fit && (m_maxk > 0.0f)) ? (1.0f / (1.0f + 2.0f * m_maxk)) : (1.0f / (1.0f + m_maxk));
  m_dk4[0] = 4.0f * (m_k[1] - m_k[0]);
  m_dk4[1] = 4.0f * (m_k[2] - m_k[1]);
  m_dk4[2] = 0.0f; /* unused */

  mul_v3_v3fl(m_k4, m_k, 4.0f);
}
